This invention relates to an insulating enclosure for a ceiling opening, and more particularly, to a cap-like enclosure for a ceiling opening of the kind associated with a pull-down folding stair.
As is well known, pull-down folding stairs are often used for access, in homes or other building structures, to overhead areas such as attics or the like. Typically, such stairs fold or retract upwardly into a frame secured between the joists of the structure, and the folded stairway is covered when so retracted by a panel associat,ed with the ceiling. Folding stairs of the foregoing type are favored for use in connection with areas to which access is only occasionally required, because, unlike conventional fixed stairways, folding stairs take up no floor space.
It has been found that folding stairs and the enclosures in which they are typically mounted are difficult to insulate, and can account for relatively high heat losses. This is so because the area of the frame into which the stair folds, unlike surrounding areas between structural joists and above ceilings, is devoid of insulation. The thin cover panel usually associated with the stair provides little resistance to heat loss by radiation, conduction or convection. The problem is made more acute in situations in which the ceiling with which the stair is associated divides an inhabited, and therefore heated or cooled, space, and a space which is not temperature controlled or is in communication with ambient atmospheric conditions.
It has also been observed that the nature and construction of folding stairs makes it difficult to insulate such stairways merely by adding conventional insulation. Because it is necessary to have access through the ceiling opening in which the stair is mounted, conventional roll insulation cannot readily be used. Moreover, insulation lying above the stair and the ceiling opening would creates difficulties with access to the overhead space, and is not, in any event, particularly effective. One reason for this is that in the folded position, the stair mechanism usually extends well above the floor line. Therefore, a simple blanket of insulation, laid over the opening, is ineffective, because the stair mechanism lifts the blanket from the floor when the stair is closed.
In view of the above, it has heretofore been proposed to provide insulating caps or covers for folding stairs. In this regard, U.S. Pat. No. 4,281,743, issued Aug. 4, 1981, to George C. Fuller suggested an insulating enclosure, fabricated in several embodiments from foamed plastic polymeric material, held together by tongue and groove joints.
U.S. Pat. No. 4,312,423, issued Jan. 26, 1982, to Earl G. Helbig, suggested the use of foamed material as an internal liner for an insulating cap, the cap itself being made of corrugated paper or other suitable material. In U.S. Pat. No. 4,344,505, issued Aug. 17, 1982, to Waters et al., it was proposed that an insulating cap be made of expanded polystyrene, the top of the cap being a slab-like member, hingedly secured to a rectangular frame.
U.S. Pat. No. 4,151,894, issued May 1, 1979, to Robert A. Edwards, suggested a rigid insulating cap, provided, however, with wheels to facilitate its rolling removal from the area around the ceiling opening.
Other insulating enclosures, caps or devices are illustrated in U.S. Pat. Nos. 2,321,499, issued June 8, 1943 to Marschke; 4,299,059, issued Nov. 10, 1981 to Smith; and 4,337,602, issued July 6, 1982 to King.
Prior art arrangements have generally, once installed, been made up of one large unit, requiring substantial additional head room and/or floor space to accommodate the cap or cover in its open position. By contrast, the present invention requires no additional floor space, and, in a presently preferred embodiment, needs only twenty-six inches (26") of headroom over the opening.